Power Aware Routing in Mobile Ad Hoc Networks

Network Simulator NS2

Quality of experience (QoE) is the perceptual quality of service (QoS) from the users' perspective. For video service, the relationship between QoE and QoS (such as coding parameters and network statistics) is complicated because users' perceptual video quality is subjective and diversified in different environments. Traditionally, QoE is obtained from subjective test, where human viewers evaluate the quality of tested videos under a laboratory environment. To avoid high cost and offline nature of such tests, objective quality models are developed to predict QoE based on objective QoS parameters, but it is still an indirect way to estimate QoE. With the rising popularity of video streaming over the Internet, data-driven QoE analysis models have newly emerged due to availability of large-scale data. In this paper, we give a comprehensive survey of the evolution of video quality assessment methods, analyzing their characteristics, advantages, and drawbacks. We also introduce QoE-based video applications and, finally, identify the future research directions of QoE.

From QoS to QoE: A Tutorial on Video Quality Assessment

Position-based routing is considered to be a very promising routing strategy for communication within vehicular ad hoc networks (VANETs), due to the fact that vehicular nodes can obtain position information from onboard global positioning system receivers and acquire global road layout information from an onboard digital map. Position-based routing protocols, which are based mostly on greedy forwarding, are well-suited to the highly dynamic and rapid-changing network topology of VANETs. In this paper, we outline the background and the latest development in VANETs and survey the state-of-the-art routing protocols previously used in VANETs. We present the pros and cons for each routing protocol, and make a detailed comparison. We also discuss open issues, challenges and future research directions. It is observed that a hybrid routing protocol is the best choice for VANETs in both urban and highway environments.

A survey on position-based routing for vehicular ad hoc networks

Data deduplication, an efficient approach to data reduction, has gained increasing attention and popularity in large-scale storage systems due to the explosive growth of digital data. It eliminates redundant data at the file or subfile level and identifies duplicate content by its cryptographically secure hash signature (i.e., collision-resistant fingerprint), which is shown to be much more computationally efficient than the traditional compression approaches in large-scale storage systems. In this paper, we first review the background and key features of data deduplication, then summarize and classify the state-of-the-art research in data deduplication according to the key workflow of the data deduplication process. The summary and taxonomy of the state of the art on deduplication help identify and understand the most important design considerations for data deduplication systems. In addition, we discuss the main applications and industry trend of data deduplication, and provide a list of the publicly available sources for deduplication research and studies. Finally, we outline the open problems and future research directions facing deduplication-based storage systems.

A Comprehensive Study of the Past, Present, and Future of Data Deduplication

Live video streaming over vehicular ad hoc networks (VANET) is an attractive feature to many applications, such as emergency live video transmission, road-side video advertisement broadcasting and inter-vehicle video conversation. Though vehicles have ample bandwidth, computation and storage capacity to support data intensive communication, the high mobility may cause persistent network partition. The performance of video streaming suffers from the delay and packet loss incurred by the long time disconnection. Although many solutions have been proposed to handle the high mobility problem, few of them addressed the problem in the context of video transmission. In this paper, we focus on video streaming between vehicles in highway, where the traffic density is adequate to mitigate frequent link disconnections and persistent network partitions. We study the performance of video streaming under different data forwarding and buffer management schemes. Real video data and the dedicated short range communications (DSRC) are used in the simulation study to better match the reality. The result of this paper gives insight for the design of the future inter-vehicle video streaming system.

Performance Study of Live Video Streaming Over Highway Vehicular Ad Hoc Networks

A vehicular ad hoc network (VANET) is a highly mobile wireless ad hoc network that is targeted to support vehicular safety, traffic monitoring, and other applications. Mobility models used in traditional mobile ad hoc networks cannot directly be applied to VANETs since real-world factors such as road layouts and traffic regulations are not considered. In this paper, we propose a vehicular mobility model that reflects real-world vehicle movement and study the performance of packet-routing protocols. First, we study the routing in small-scale VANETs and propose two routing schemes: (1) connection-based restricted forwarding (CBRF) and (2) connectionless geographic forwarding (CLGF). With the insights obtained, we consider routing in large-scale VANETs. Since road complexity and traffic variety may cause many potential problems that existing routing protocols cannot address, we introduce a two-phase routing protocol (TOPO) that incorporates road map information. The proposed protocol defines an overlay graph with roads of high vehicular density and access graphs that are connected to the overlay. While in the overlay, packets are forwarded along a precalculated path. As far as access routing is concerned, we employ the aforementioned CBRF and CLGF schemes and send packets to the overlay or handle packets delivered from the overlay. We argue that the TOPO can serve as a framework that integrates existing VANET routing protocols. We also consider data diversity in VANETs and design the TOPO as an intelligent transportation system (ITS)-friendly protocol. To validate our design philosophy and the routing protocol, we use different areas in the city of Orlando, FL, and generate vehicular mobility traces, following our mobility models. We feed the traces to network simulators and study the routing behavior. Simulation results demonstrate the performance and effectiveness of the proposed routing protocols for large-scale VANET scenarios.

Small-Scale and Large-Scale Routing in Vehicular Ad Hoc Networks

Storage systems and methods to improve space saving from data compression by providing a plurality of compression processes, and optionally, one or more parameters for controlling operation of the compression processes and selecting from the plurality of compression processes and the parameters to satisfy resource limits, such as CPU usage and memory usage. In one embodiment, the methods takes into account the content-type, such as text file or video file, and select the compression process and parameters that provide the greatest space savings for that content type while also remaining within a defined resource-usage limit.

Systems and methods for selecting data compression for storage data in a storage system

A vehicular ad hoc network (VANET) is a high mobility wireless ad hoc network that is targeted to support vehicular safety, traffic monitoring, and other commercial applications Mobility models used in traditional mobile ad hoc networks cannot be directly applied to VANETs since real world factors such as road layouts and traffic regulations are not considered In this paper, we propose a vehicular mobility model that reflects real world vehicle movement on the road Based on the mobility, we study the performance of existing Mobile Ad Hoc network (MANET) routing protocols, ie, AODV and GPSR We observe the drawbacks of the MANET protocols and argue the inappropriateness of directly applying those MANET protocols to VANETs We also propose simple modifications to these protocols which make them more suitable for small scale VANETs When investigating the large scale VANETs, we introduce a two phase routing protocol that incorporates map information The proposed protocol defines an overlay graph with roads of high vehicular density and forwards packet along the pre-calculated path in the overlay The access, which is the rest areas relies on our modified small scale routing protocols to send packets to overlay  Both small and large scale routing protocols are validated with simulation We generate vehicular mobility traces for different road layouts in Orlando by making vehicles follow the mobility model We feed the traces to network simulators to study the routing behavior Simulation results show the performance and effectiveness of our modified and proposed routing protocols for VANET scenarios

An Integrated Study on Mobility Models and Scalable Routing Protocols in VANETs

It has long been acknowledged that TCP performance suffers in hybrid networks. A Split TCP approach has been proposed to address this problem. In this approach, a proxy is employed at the boundary of wired networks (e.g. the Internet) and wireless networks (e.g. cellular networks, WLan or mobile ad hoc networks). This strategy significantly improves TCP performance. However, it does not maintain the end-to-end semantics of TCP. The loss of end-to-end semantics may cause problems to applications that rely on such a guarantee provided by TCP. In this paper, we introduce a novel technique called Semi-Split TCP to address the problem without sacrificing the benefits of Split TCP. We present the architecture and algorithms of the proposed technique; and give implementation, simulation, and analytical results to illustrate the feasibility of this method. Our simulation results demonstrate that Semi-Split TCP can achieve similar performance as Split-TCP without sacrificing the end-to-end semantics.

Fei Xie

Papers

Performance Study of Live Video Streaming Over Highway Vehicular Ad Hoc Networks

Small-Scale and Large-Scale Routing in Vehicular Ad Hoc Networks

Systems and methods for selecting data compression for storage data in a storage system

An Integrated Study on Mobility Models and Scalable Routing Protocols in VANETs

Semi-Split TCP: Maintaining End-to-End Semantics for Split TCP